/**
 *		Licensed to the Apache Software Foundation (ASF) under one
 *     or more contributor license agreements.  See the NOTICE file
 *     distributed with this work for additional information
 *     regarding copyright ownership.  The ASF licenses this file
 *     to you under the Apache License, Version 2.0 (the
 *     "License"); you may not use this file except in compliance
 *     with the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *      Unless required by applicable law or agreed to in writing,
 *     software distributed under the License is distributed on an
 *     "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 *     KIND, either express or implied.  See the License for the
 *     specific language governing permissions and limitations
 *     under the License.
 *     
 *     Image Resizer Project
 */
package image.resizer;

import java.util.ArrayList;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * Event manager for item comletion events.
 * Redestribute events for listeners, that subscribed
 * to receive progress information. 
 * @author Ilya Dudarev
 */
public class ProgressEventsManager implements IProgressListener {

	private static final int MAX_THREADS_NUM = 5; 
	private ArrayList<Runnable> listeners;
	ExecutorService executor;
	
	public ProgressEventsManager() {
		listeners = new ArrayList<Runnable>();
		executor = Executors.newFixedThreadPool(MAX_THREADS_NUM);
	}
	
	public void itemCompleted() {
		if(listeners.size() > 0)
		{
			for(Runnable listener : listeners)
			{
				executor.execute(listener);
			}
		}
	}
	
	/**
	 * Subscribes listener for receiving progress events. 
	 */
	public void appendListener(IProgressListener listener)
	{
		listeners.add(new RunnableProgressListener(listener));
	}
	
	private static class RunnableProgressListener implements Runnable{
		private IProgressListener innerListener;
		public RunnableProgressListener(IProgressListener listener) {
			innerListener = listener;
		}
		public void run() {
			innerListener.itemCompleted();
		}
	}
	
	@Override
	protected void finalize() throws Throwable {
		executor.shutdown();
		executor = null;
		super.finalize();
	}
}
